This project is a long term committment to studying the regulation, transcription, termination and processing of stable RNAs. The tyrosine tRNA genes of E. coli have been chosen as a model system that is already highly developed for genetic as well as biochemical approaches; however, the experiments are intended to afford insights of general relevance and applicability. Mutations in the tyrosine tRNA1 promoter will be isolated and characterized biochemically. In particular an effort will be made to identify and study those sites unique to stable RNA promoters and/or involved in the regulation of transciption (for example, in the stringent/relaxed response). Mechanisms of transcription termination will be studied in vitro rearrangments of the repeated sequences in the distal end of the tyrT gene that contain three potential termination sites. In particular the features which make this site Rho-dependent will be analyzed along with the relative importance of sequence versus secondary structure. Steps in the processing of native tRNA transcripts will be analyzed with special attention to characterizing new intermediates, identifying new processing enzymes and investigating the possibilities of regulation at this level of gene expression.